Supervisory system



Feb.: 8, 1927- D. A. QUARLTES SUPERVISORY SYSTEM Filed Feb. 14, 1925 2 sheets-sheet" 1 Cil , 'and1 amplified yreceiving Vmay be obtained'V v ingqas indicatedain Figl6gor, o nthe lOthe'r lhand by? mov-ing' key;4 35' to operate its Ileft layf'GOJ-Theuse of gthe relayGO avoids oh-l circuit traced Iab 'the' *receiver-.Y1

circuits-traced presentlyy ther ditions-vheing then `as 'indicated inFigi 17.A

"pedances of the line and auxiliary'resistance- 'coil 66', 'r'zonductor''677 middle 'right hand 'a'rmature of relay' 51, conductor 168,' tip con-1vv 'currentgcircuit for the transmitterp-is .thenl causes eneigizatien oit receiverf 301 over the' 1 ove between WindinggflS fand'f lWith#1plngsw31 -in jacks 32,if hey `361i'emoved tov operatefjits rightfhandY contacts relays ,liand 60 operate; and if lleys 35v and V37 loe-vin their- 'normalpos'itions and plugs i 26 and 27be in jacls'24- and 25,;"theioperaY-w tionof these relays, in conjunctionfwitfh kthe operation 'of the right hand contactsof key 36,'arranlges the circuits as indicated in Fig: l 5,Y for talking and amplified. receivingl in both Vv directionsyksiinultaneously, over circuits traced presently.v Then,l ihy; moving key i 35 to operate its right. hand contacts, talking with respect lto lineV 11v only, over circuits traced' presently, l the, vcircuitV cond-itionsihehand contacts, instead of vits Lrightlha'ndcontacts,v talking yand `amphiicdreceivingzg mayV bei obtained with respect tofline 13 only, over uit ,con-

The circuit when arranged as indicated-'in Fig. 5 operates 1n the sameV rgeneral manner as the circuitfof Fig-1 zof'vG.- A. Campbell;

Patent1,254,472vJanuary 22 1918,the im? of vthe patent,l however, having their-places taken'by tlie'impedances presentedloy- Wind ings '2O and 19 of the applicants drawings, anch-further, the applicant employing a re'- sistancc 92-'in shunt to .receiver 30,1501' a purr* pose*explainedy hereinafter.` i A Tlieoperationf of Atherighti hand contacts#` jectionableclicks in receiver duc/to operatingfkey 36;," TheV operation` of relay 51 also energizes transmitter 33- overlra 'cir-f cuit from ground through hattery, choke ductors of vupperfjac'k 32 and plug 31, transmitter 33,z tip conductors 'of lower `plug'31j" and 4jack 32-to ground. fThe opei-'ationgof'thew right handV inner andoiiter armatures'ot Vrelay 51 disconnects the circuitoic condenser` @and Winding 18ct transformer 34, from; thefreceiyer` Y-v and :connects that circuit across the transmitter. :Thea alternating from groundithrough righ-t *hand 'rmakefcon-Yr tact' fof "relayll 551", y-cond uctoiw55,\ Winding 48 i jot transforiner` 34,; condenser-A 49,5 '.con'dnctor l 50,= makeE contactotrelayi.; 51,1: conductor :67,1

Vmake ContactA 01trelay 51;-f1conductor g-tip.

conductors Aof upper acky 4P32 lZand .plugf 31,l

transmitter;33;` tipi vconductors fof lower. plug ai 43 1 andjack '32,3150 ,groundy Thefhighzj'imped'an'ce Winding; 44 of 'transformer 311 has v.

an end terminal 7 6,11tapconductor's,'L77, 278WV erationof rela y connects the tapfeonductor'78- directly to fthel sleeve conductor; of upper Vjack 32,ffand thence through 'the .Isleeveconductor of: upper plug V31 toone terminal fof receiver =.'-Preferably .ther` num-loer of "turnshetween tap conductors- 771and 178f'is equal tothef'number ybetween :tap conductors 1i Y Y With' the system of Fig. `in the condition indicated in-Figgf, the keys 35'Iand 37 bei-1.

Linglinithe'irnorinal positio'nsfand theA right@y handcontacts fofkey -36'bei1ig operated, currentssent Ythrough,i'vinding 18 of'tians'liorm-` l er "34: from 'transmitter l-3'3 over thel circuit tracedji1st=ahove,V canse -energization of lwindings -19fand'20 over 'a circuit from vtap .conductor 7 7 through conductor 81, contact of hey 35,conductor- 82,1 vcontact of: key 36, conductor 7, right and left :hand contacts f of hey-37;tip'conductors of plug26 and'jacl';

2li; terminal-1521,. fWi-ndi'ng 20;y Windingl 19,'V ter1n1nal'23, ring conductors yof'vacks24V 'and 1 `125 `and f plugs'f-26'fand '27', conductor 40, make' contacteer -keyl 36,'y conductor 83, break-icon- "tact ofliey1-35L;andiconductor 84,1`tov tap con-v y dnctorj ,79.* "The currentsthi'i's: :produced in i Winding-20 -lrom i transmitter 33 VV'cause cori respondingv currents in lineV section l11 and in l1 8 *and output circuit- E*0i amplifier 17; hued-o notlca'usefan llfMiFgto'bc applied to the linput f ofamplifier -15 since` 1 the* input Winding Similarly, the' 4currents pro-v ducedf in fWind-i'ngf 19V `from transmitter .'33

' circuit of amplifierV 15 vis conjugate to vthef cause corresponding current-s 2in y-line section 13 'and network l111,- and in Wind-ing 161and` output circuit of ampliiier- 215, but not .in the inputcircuit-of ampliiienl (Thus-,fourrents fromu dief-transmitter# are r sent` over ihothf-line sections 11 ,and 13 simultaneously.

lilith "the system in thecondition indicated 1n Eig. 5, as just i'etcrred to ampliied/receiv ingy Q tran'smission pass-ing from line section -i Y i .12()V 'HQ 11 tollii'ie section-13 will he obtained oyer'tho following circ-mts? '.Nrves from 1yr-line` -1 transimttedthrough amplifier' 15 natu/1nding' 16,- inducenink Winding@ augV which sendscurrentforeifacircuitj'fromter- 7 nun-'atV 23 through sleeve 'conducto off'iaclc ndfl25 and vplugs26 and2`7," conductor-'140;' make fcontactfo't key- 36,-conductorI 83,' break` mei-143425120 tap r conducto-14178,'whence. thereincuit continues through two branches in par-- One of these branches conductor 90. The other of the two par- From the latter conductor, thecircuit for;

allel branches extending from tap conductor 78 is through conductor 91, a resistance 92,

right and left hand contacts of key 35, conductor 93, and key 36 to conductor 90.

the current of the two branches extends through conductor 56,. right and left hand contacts of key 37, tip contacts of plug 27 and jack 25, terminal 22, and winding 19. This current iiowing in the part of the wind-` ing 44 of transformer 34 between tap con-- ductors 79 and 7 8, induces an E. if. F. inthe part of that winding between tap conductors 77 and 7 8, and consequently tends to cause current t'o-flow through a circuit extending as follows: From tap conductor 78 over the circuit just traced (including receiver 30 and resistance .92, in parallel) to terminal 22, thence through winding 20, terminal 21, tip conductors of jack 24 and plug 26,'leftl and right hand contacts of key 37, conductor 47 inakepcontact ofkey 36, conductor 82, break contact of key 35, conductor 81, tap conductor 77 and the part of the winding 44 of transformer 34 included between tap conductors 77 and'78. vl'lowever, this tendency for this curi'ent to tio-w is neutralized by the voltage dropVV produced across receiver 30 and resistance 92v bythe current from coil 19. The current flowing from winding 1 9 through the part of transforii'ier 34 between taps 79 and 78 induces in winding 48 a current which flows over the circuit traced above through transmitter 33, condenser 49 and winding 48. As may be seen from consid-' eration of the applicants system with equation 8)A on page 5y of the Campbell patent mentioned above, the condition that the winding 20 be `connected to points of equal potential with respect to an electro-motive force applied from winding 19 to terminals 22 and 23, requires a certain ratio between the impedance facing the low impedance winding of transformer '34 and t-lie impedance 'facing terminal 22 and tap conductor 78 from the direc-tion of receiver l30, provided the windings of transformer 34 are fixed. yMoreover, the impedance facing terminal 22 and vtap conductor 7 S'from the direction of receiver `30 should be of such value that thel conjugacy just mentioned obtains througliout the range of the frequenciesreceived by winding y19. The resistance 92 serves to I maintain this impedance more nearly at this value than would the impedance of merely the telephone receiver, which ordinarii sleeve conductors of upper jack `32 andY varies considerably with frequency. The input circuit of ainpliiier 15 is conjugate to .the winding 20, and therefore any current vappearing in winding 20 because of Yfailure circuits of the system being in the conditionr indicated by Fig. 5, is similar to the operation, just described, for amplified receiving of transmission passing from line section 11 to line section '13, and the circuits involved may be traced as follows: Waves from line l 13, transmitted through amplifier 17 and winding 18,'inducein winding 2O an E.l M. l?. which sends current over acircuit traced above between terminal 21 vand tap conductor 77, current continuing through the part of the high impedance winding 44 of transformer 34 included between tap conductors f 77 and 78, and thence over a circuit traced above between tap conductor 78 and terminal 22 including receiver 30 and resistance '92 in parallel, the circuit for this current continuing thence through winding 2O back to ter-V minal 21. For reasons made apparent by the above description of .the operation of vob-V taining amplified receiving of transmission.

passing from line 11 to line 13,110 current should flow in winding 19 whenamplitied receiving of transmission passing from line A13 to 'line 11 is being obtained as just described,

and any such current appearing in winding 19 as a result of improper adjustment of the circuits will reach the input of amplifier 17 only in greatly diminished amplitude, sincethe winding 19, line winding and network winding of transformer 16 render the input circuit of ampliiier 17 conjugate to the impedance facing winding 19 from terminals 22 and 23. In the above description of the operation iiok in transmitting from transmitter 33 to `both lin-e sections simultaneously, with the circuits of the system in the condition indiy catedrin Fig. 5, no mention was made ofthe receiver. The circuits of the receiver having now been traced, it will be apparent that'in that sending operation, the receiver is in anti-side tone relation to the transmit#l ter, as is indicated in Fig. 5. VThis relation results from the `facts that the. impedance facing terminals 21 and 22 from winding 2O is equal to the impedance facing terminals 22 and 23 from winding19, and that the current produced inthe low impedance winding 48 of transformer 34 by transmitter 33 in'- duces equal E. '.M. FFS in the two parts of the winding44 between tapl conductors 77 and 78 and tapconductors 78 and 79. Reference may be had to the Campbell patent mentioned above fora detailed discussion of the theoryunderlying the anti-side tone relationship in circuitsof this generali-character. The circuit arrangement indicated in Fig. 5 of this lapplication is like the circuit arrangement ldisclosed in my patent mentioned above, Vexcept that "the patentdiscloseslno element correspondingto the riesistance 92 of this application.

As noted above,vvith the system inthe condition indicated in F ig. 5 as, just described,

Y Vtherepea-ter attendant can arrange the circuit in the manner indicated in F ig. 6v by moving key35 to operate its right hand contacts. That is, the circuit condition represented in Fig. 6 is obtained When key 37 is in its normal position, lthe right' hand con tacts of key V36 areoperated,and the right hand contacts of key 35 are-operated, with plugs 26 and 27 in jaoks24'and 25 and with plugs 31 in jacks 32. y As noted above, this is the vcircuit arrangement employed by the attendant for talking andl anipliiied receiv-4 ing, with respect to 4line 13'only.V rThe operation in talking is as (follows: Currents from transmitter 33 energize the low impedance winding`48 ot' transformer 34 over the energizing circuit' traced above between those` elements. Consequently, there is induced .in the portion of the .high impedance Winding 44 of transformer 34 vv'between tap conductors 78 and 79 an E. Mgl?. `'which sends current through Winding19 over a circuit extending from tap. conductor, 79 Vthrough conductor' 84, key 35, conductor33,

" key 36, conductor 40,' sleeve conductorsV ot plugs 26 and 27 and jacksV 24 and 25, terminalj23,r\vinding 19, termin'al22, tip conductors of ljack 25 and plug 27, lett and vright hand contacts of key 37 ,conductors 56A and 90, make ycontacts of kleyj36,'conductors V39.

and 88, break contact of key 35, make contact oiifkey'35, conductors 94 :and 91, tap conductor 78, and the portion of the high impedance Winding 44 of transformer 34 -between taps 7 8 an'd79`. This/current in lWind ing' 19induces E. ll/I.- Fis inthe Vline and :network .windings ,of transi'or'nier 16 which cause current to ilow inline sect'ionf13'ancl" network 14, but not, intheinput circuit or amplifier-17 and thence"through,amplifier circuit of amplifier y15. In this condition ot 'the circuits ot the system, amplified receiv-V ing'. 'from line section'13 may take Vplace as follows: l/Vav'es-from' vline section 13""are,rv transmitted through amplifier V17 andWind-l ing 18, inducing in 'Winding 2() an E. M. lt.

Athrough tip conduotorso-t ack 24`and vcuit extending'V from tapV` conductor y vthrough conductor 81', key 35,'cond`uc`tor 82,2 l.key 36, conductor l47,y right and 4lett ,hand contacts of. key 37,tip conducto'rsrio't plug the system the transformer 1G causes the vre- "system the transformer 18 causesy thereceivv which causes currentl to energize. receiver 30 vover .a circuit fextending' from y ,-termii'ial l 21 2G, lett Aand righthandcontacts of key37, conductor 47, make `contactfoi" key 36, conductor' 82, makecontact of 'key 35, sleeveconductors of low-er jack 32 and'pl'ug 31, receiver 30,sleeve conductors of upper plug elia-iv 31v and jackf32, conductor 52, contacts of re`v lay 60, conductors 91 and 94, .make'contact of key 35, conductor 95, break `Contact key 3.5, conductors 88rand 89, make cont-actsV `of key-36, conductors 90 and 56, right `and lleittthpand contactsl ot key `37," tip conductors ot plug y27 and jack 25, terminal 22, and

Windingl 20, toterminal V,21. Of Course,

Waves :trom` line sectionl 13 also 'induce E. M. Ffsrin lvvinc'lings V1G/and 19, the

E. M. in 'Winding 16 causing' vcurrent to flow 1n the output circuit ofamplilier 15and to tlow inthe circuits justtraced' bet-Ween ltransi'nitt'er 33 and Winding 19.

As noted above, the circuit-'condition indicated 'inFigz 7 is obtained vvhenkey 37 is in its normal posit-ion,.the right hand contacts o 'Y key f36 are operated, and the .le-ft jhand contacts ot key' `are operated, and thiSls the circuit arrangement employed `by the attendant for talking and ampliii'ed receivtheE. F. in Windingr 19 ,causing current ing with respect to line section 1"'1f.onjly.f

The operation in talkingis' `as l i"ollovvs Currents trom tranmitt'er 33 energize the low Viinpedai'ice Winding 48 orf 'tfajngfgrmer 34:1 over the :energizu'igclrjcuit tracedabovej beioo tvvefenl those element-s. Consequei'i'tly there' is induced in the portion ot the high impedance Winding 44 of transformer 34 between tap- ,Y

ksends current through Winding 20ove'ra 'cir- 26 and jack 24,. terminal 21, Winding 20",

terminali 22,'tip .conductors of jack 25 and plug 27lettand right hand contacts of key jconductor's 77 and 78 .an M4 F. fivhidhl 37,c'onductorMikey/"36,conductors'89 andgj, i i

make cont'actot' key v35 condutcor91, tap

conducto-r 7S, and the portion of vthe high impedance Winding 44 ot transformer 34 be ttveen 'tap conductors V73 and This cur- ;rent'in Winding '20" induces E. F.s in 'the liney and networkwvindings 'of transformer 18, which `,cause currents to jfloiv in line sjeetion 1 1 `and n`et`Work12, but notgin thelinput Circuit of amplifier 15,Lsince,as pointed'oi'it ."above, that. circuit is .conjugate Yto Winding 20.

Thus, in'ithis condition .ofthe circuits of the er i0 be in iUlti-Side tone relation to the* transmitter.' The Acurrent in Winding 20ct' course vinduces in' Winding 13fan E. F. which causes'currentto lovvii'n the output circuit of amplifier 17 .In this condition,ot4

`the circuits of the system,'amplifled receiving from line section llamay take place as follows: Waves from vline section 11 are are transmitted through amplifier 15 and winding' 16, inducing in winding 19 an E.

M. F. which causes current to energize receiver' 30 over a circuit extending from terkminal 23 through sleeve contacts of jacks 24 Y receiver 30, sleeve contacts of upper plug 31 andjack 32, conductor 52, contacts of relay 60, conductor 91, make contact of key 35, conductors 88 and 89, key 36, conductors 90 and 56, right and left hand contacts of key 37, tip conductors of plug 27 and jack 25, terminal 22 and winding 19, to 'terminal 23. Of course, waves from line section 11 also induce E. M. F.s in windings 18 and 20, which cause currents in the output circuit of amplifier 17 and in transmitter 33.

When the repeater attendant desires to communicate with a line section 11 or 13 directly instead of through transformers 16 Land 18, he inserts plugs 26 and 27 in jacks 28 or 29 and moves key 36 to operate its left hand contacts, vwith keys 37 and 35 in their normal positions. Upon such operation of key 36, conductor 62 is grounded through conductor 97, in a manner corresponding to that in which conductor62 was grounded through conductor 61 'when the right hand contacts of the key were oper- Y ated as described above. Assuming that it conductor 78.

is line section 13 with which communication `is desired, the plugs are inserted in jacks 29. The circuit will` then be as indicated in Fig. 8, except that in Fig. 8 the plugs Vare shown as merely positioned for inser tion in the jacks but .not inserted therein. lith the plugs inserted, the operation Vof the system in transmitting' from transmitter 33 to line section 13 is ag follows: Currents from transmitter 33 energize the low impedance lwinding 48 of transformer 34 over the,

energizing circuit traced above between those elements. Consequently there is induced in the high impedance winding 44 of the transformer an E. M. F. which causes current to iow to the yline section 13 over a circuit extending from terminal 78 through part of winding 44 to terminal 76 and thence through conductor 45, break contact of key 35, conductor 46, break contact vof key 36, right and left break contacts of key 37, tip

conductors of plug 26 and upper jack 29,`

line section 13, tip conductors of lower jack 29 and plug 27, left and right contacts of Vkey 37, conductor V56, make contacts of key 36, and thence through two branches to tap through conductor 43 to terminal 80 and through part of winding 44 to terminal 78.

One of these branches isy ceiver 30, sleeve' conductors of upper plugf7( 31 and jack 32, conductor v52contacts of relay 60, and conductor 98, to tap conductoi` 78. However, substantially no current flows'in this latter branch, since it is conjugate to the transmitter, the portion of winding 44 between terminal 80 and tap conductorl 79 having included therein resistance of .such value as to approximately balance the impedance of line section 13. This antiside tone arrangementof the system, as indicated in Fig. 8, issimilar to the circuit arrangement of Fig. 4 of the Campbell patent mentioned above. However, in the applicants Fig. 8, the resistance for balancing' the line resistance preferably does not ex-A tend within the'part of winding 44 included between ta conductors 7 9 and 78 since that part is to be employed in the circuit arrangements indicated in Figs. 5 and-6 in 2, it assists in preventing any undue amount of feed back from the output to the input of an amplifier, in the manner pointed out l above in the description of the operation of that circuit arrangement. ln the circuit arrangements indicated in Figs.l 2, 3 and the transmission loss caused by monitoring is further reduced by reason yof the fact that the entire winding 44 is in circuit, so that the ratio of the effective turns'V in winding 44 to the turns in winding/48 is greaterl than when the circuit is conditioned as indicated in Figs. 5, Gand 7. It is especially important thatthis loss be small when each of a large number of repeaters in tandem in lli a line is provided with monitoring apparav 'Y tus.` Otherwise simultaneous monitoring at a large number of the repeatersmight cause the total transmission loss due to monitoring to be excessive. Yivith the circuit arrangements indicated in Figs. 5 to 7, the number of turns `of winding 44'included in circuit is such-as to giveV the proper impedance relations for efficient.transmisslon,

from transmitter 33through transformers 34, 16 and 18 to line sections V13 and 11, as well .as the proper impedance relations for anti-side tonev transmission as. described above. With the circuit arrangement indicated in Fig. 8.V the ratio of the effective fifi' Ythose portions may Y '1g-e lessee primary and secondary turns ot transformer '311 is 'such as to give eliieienttransniission from 'transmitter 133 and transformer 341 vdirectly to the impedance `of linej13 augn'iented by theresistan'ce in winding-L14. l

' From the explanationv above' ot' the operationof the circuit arrangement indicated' in Fig. 5 in receiving Vfrom a vline section through an amplifier, with Vreceiver the operationof the circuit arrangement indicated in Fig. 8 in receiving directlyY from a line section', with receiver 30, will be parent without further explanation. This last mentioned operation is in laccordance with the' operation indicatedy at Fig'. 3 of the Campbell patent mentioned above.

lVith plugs 26V and 27 in jacks 28 or 29 of a line arranged 0r,say 20"or cycle y ringing, operation -vof' key 3,7 in one direction or the other will send Yringing current' ot the proper frequency out on the line, over circuits obvious from inspectionv ot the drawing, 'operation of the left hand contacts oit key 37 sending out say 20 cycle currentfrom source 38 and operation of the right hand contacts of key 37 sending out say 133' cycle current from source 39. Fig. 9 shows Va four wire circuit comprising afourwii'e 'repeater R aiidterminating in two two-wire telephonel linesV 1 11 andV The repeaterl R comprises .a one-way 113. ampliier'll, between a section'101 and a section 102 of one side' of the four-wirefcircuit, for amplifying transmission passing Vfrom line v111 to line 113, and alsocomprises a one-way ampliiier 117, between a` section 103 and a section 1011 of the other side ofthe tourw'ir'e circuit, for amplify? ing transmission passing from' line 113 v'to linel 111. "The dotted portions yor' line sections 101, 102, 1,03 and104 indicate that be of f :onsiderable length.

peater R and described presently.- The fourdot and dash lines 114A and BB`. .'The four-wire circuit is joined `to the termina-ting two-wireline `113 by 'hybrid' coil or threeY winding transformer 116V and liner balancing network 114 in the usual manner; and'` is similarly join-ed to line 111 by the hybrid coil 118 and 'line' balancing 'network' 112. The hybrid coil 116 comprises the usual 1in-e series lwinding, the Vlat-ter being'designated 118". An output transformerfll?, having a primary winding 1161, a secondary windling' 116c and 4al third or monitoring winding119 is providedV with terminals `dcated in'Figs. "5, a Vthe, amplier inps-t circuit connectedto the Of course, those portions may invcliid-e other repeaters such as R; and such other repeaters maybe `provided withsupe-r- V visory apparatus of Vthe type used 'at re-s in g119, is provided oran'ipliiier 115;:and a l'similary output 'transformer 11.3% having a primary Vwinding-118, a lsecondary winding 118 and a third or monitoring winding 120, 4is provided'for amplifier 117.

Y y 122 and 123;.and winding 120-is provided withter-n minals 121 and 122. Y Thesethree terminals are for connecting windings 119 and 120 toy jacks such jas 24 and -25 shown iii Fig. `1, so that theserwindings and terminals may cooperate with the plugs 26 and 27 and the attached supervisory` apparatus oI"F `-ig.1 in the same manner'as do terminals21, 22 and 23, and' windings 19A and 20 of Fig. 1. Y

The elements 111 to 115 and 117 of Fig. 9

yareV like elements 11 to15 and. 17,*respectivev115 and 118 embody no monitoring coils coi1k responding to the coils 19 and20 V'of Fig. 1.

lWind- However, the hybrid coils 116 and 11S-assist I in preventingv feed `back from the output to the input ot anvampliiier.through coils 119 'and 120, ini receiving-'by lreceiver 30- under the-circuit conditions indicated in Fig. .2,

ifioinfv traifismittei.l of) and i', from entering bridge ,points-01"' theirhybrid coil to which that one Y winding` transmits. The manner in "which the hybrid coils 118` and 116jtunction to accomplish ithese results is similar to the parent frointhe drawings, rwithoutr further explanation. 1n Vthe crcuit condition indiwindings 119 and-120 balances the impedance `of the other to render receiver 30 antiside tone with respect to'transmitter 33.

gThe action .of resistance shunt -92 in reduc ing undesired energyv transfer between the lines in the two di'i'ectionshas special utility in a four-wire repeating system, since a prim-e object in employing a four-wire rather than atwo-lwire circuitlisavoidance of the echo currentpaths introduced lby each repeater in a ltwo-wire system.

Fig. 10 showshow the supervisory apparatus: otFig. 1- maybe employed vwith af21- type repeater 215, connecting telephonelines. "211 and 213,- and comprising 4an amplifier' 215 and a hybrid coil216 `which vhas,.in`"adv to 'one or the windings 119and 120 under the circuit conditions inandalso preventspeech currents transmit-,ted

'ibo

manner' in which'as explained above, hybrid Q coils 18 vand"v 16 accomplish the same func- 'cated in Fig. 5, the impedance of one ofthey i Y l dition to the line windings and the winding 216', aV fourth or monitoring winding 219. A resistance 299, having an impedance Yequal to that presented by winding 219V is connected between terminals 221 and 222, in-

stead of a second monitoring winding suoli of Fig. 1 is applied to the repeater of Fig.

10, the circuitconditions indicated in Fig. 3, and the combination of key positions requisite for that condition, are not employed, since Fig. 10 has no monitoring winding corresponding to winding 20; and with the coinbination of key positions requisite for the circuit conditions indicated in Fig. 6, there can be no reception by receiver 30, and transmission is to both line sections 211 and 213 instead of to only section 213; and with the key positions corresponding to Fig. 7 there can be no transmission from transmitter 33 to either line section 211 or 213, and reception is from either line section 211 or 213,

through amplifier 215, instead of from onlyV line section 211; and with the key positions corresponding to Figs. 2, 4: and 5, winding 219 gives amplified monitoring of transmission in either direction over line sections 211 and 213;` and with the key positions corresponding to Fig. 5, winding 219gives transmission to both line sections 211 and 213. The operation of the repeater of Fig. 10 in connection with the supervisory apparatus of Fig. 1 will be apparent without further explanation, in view of the description above of the operation ofthe system of Fig. 1.

The broad features involving the general principle herein disclosed may 'be embodied inmany organizations widely different from those specifically shown and described without departing from the spirit of the invention defined in the `appended claims.

What is claimed is:

1. A two-way vtransmission system comprising two transmission sections, means including a repeater connected between said sections, a receiver, a transmitter, and means connecting saidtransmittei for transmission vto one only of said sections at a time, while connecting saidV receiver for monitoring transmission passing from said one section to the other, after said transmission has been amplified by said repeater.

.2. A vtwo-way `transmission system comprising two transmission sections, meansincluding a repeater connected between said sections, a receiver, a transmitter` and means connecting said transmitter for transmission to one only of said sections at a time, with said receiver in anti-side tone relation toV said transmitter, Ywhile connecting said re-V ceiver to receive through said repeater a portion of transmission approaching said repeater over said vone section and passing to said other section.

3. In combination, two line sections, a repeater, two transformers connecting said repeater to said sections, a receiver, a transmitter, and means, comprising said transformers, connecting said transmitter for transmission to one onlypof said sections at a time and with one of said transformers preventing said transmission from reaching said receiver, while said means connects said receiver to receive through said repeater transmission approaching said repeater over said one section.

Ll. A two-way'transmission system coinprising two transmission sections, means including a repeater connected between said sections, a receiver, a transmitter, means connecting said transmitter for YVtransmission to one only of said sections at a time, while connecting said receiver for monitoring transmission passing from said one section to the other, after said transmission has been amplified by Isaid repeater, and means Vfor. selecting the section to and from which said transmission and .reception are to ocour. Y f

5. rEhe method of operation on a system having two oppositely directed unidirectional amplifying elements for amplifying transmission between two sections of a circuit, which comprises introducing' transmission into the lsyst-ein at the youtput side of only one of said elementsat a time, for passage over said section to which said Voutput side is connected, and abstracting from said system at the output side of said other element a portion of transmission passing through the latter element to said other section.

6. In combination, al receiver, a transmitter, a transformer having two windings, and means for adjusting the impedance ratio of said transformer to one value and connectrection from said other winding to said one winding, with said ratio at the second mentioned value.

7. In combination, a. receiver, a transmitter, a transformer having two windings, and Vmeans for adJusting the impedance ratio of vsaid transformer to one value and connectingthe transmitter in anti-side tone relation "GD-itheiother of isaid l-inesthrough saidfreceiv- 1561er@ Y with the receiver to .transmit throughlsaid ntransformer inthe-direction from one windving to the other With said transformer ratio so adjusted, and for adjusting the impedance ratio ofV said transformerto a different val- -ue `and lconnectingsaid 4receiver to receive, Y

from said transformer, transmission passing Ythrough said VVtransformer in the direction from-said other Winding to saidone winding,

with said ratio, at the second mentioned value.

.8. Inlcombination, a circuit, a balancing circuit therefor, a repeater, means comprising a :transformerconnectedbetween said revpe'ater and said circuits, said transformer having'amonitoring Winding therein, a re- Aceiver, Va transmitter, a. second transformer, fsaid' second transformer Vhaving ,windings of different impedances, andnieans. for arrang-f 9. Incombinat-ion, tvvo' signaling lines, re-Y ceiving means, comprisinga receiver and a ,transformer ,having :primary yand secondary windings, for receiving signals from said "ilines, ,said linesbeingfconnected Lto said Vreiceiving {meansfin substantially yconjugate said :lines through said receiving means, and @means forfchangingfthe,connections of said c receiver fromm-one Winding of said-'transformer-tothe other. ,j i

510. Inf'combinationj` rtivo signaling lines, two-Way repeating" mea-ns v interconnecting saidyli-nes, Vmeans comprising a, non-unity` rationtransformer,connected:to said lines for ,receiving :signals therefrom, said connec-V' frtions having means :for preventing the transfer of signals from one of said lines;y

, ing .from the transmitter through 'thetransato the ,other through said 4receiving` means e and iforrchanging-the connections ofthe re-VY ceiverfrom vone side :to theother of said im- ,Y

wpedance changing transformer.

.two-Way Virepeatingg vmeans interconnecting wsa,i,cl'rlines, meansromprising a-receiver and :a .non-unity ratio transformer, for receiving c, signals zfromsaidlines, said ,lines beingrconlniected `tosaid rreceiving'means in, substan-` itiallly conjugate relationgfor preventing the @transfer 'of signals :from oneof said lines to [rela-tionafor preventing vthe transfer fof v sigi nals from oneof said'linesto thefotherofy ing.means,and nieans for changing theconnections of the receiver from onesidelto the other .ofsaid ,impedancevchanging transformer.. 'c i j' l2. In combination, two signaling lines, Vmeans' for ,receiving gnals from -said -lines and ,transmitting signalsto said lines, said ,means comprisine` a receiver, a transmitter andai .non-unity ratio transformer, said lines being connected to said-*means in sub- Astanti'ally conjugate relation for preventing .the transfer of signals from one of said 'lines 4tothe other ofsaid lines through said Ineens," Y

and means for Ychanging the connections' of lsaid :receiver from one side to the'. other of no said impedance changing transformer. ,n

'13. In combination, tivo signalling 'lines arranged for j transmission of signals f from 4.one to the other, means.l comprising a transvmitter and a receiver in conjugate relationaa Vand comprising a transformer vhaving Wind- 'ings 'of different impedances. for receiving vsaid lines, said linesbeing connecteduto said 'l Y receiving means 'in si-ibstantiallv coniugateneV relationfor ,preventing the` transfer of energy from one of said linestojtheother .Y of said llines throughv saidl receiver@V and means for changing the connections of said Vreeeiver from one 'Winding vof saidtrans-9a former to the other.

Y .14. Ina tivo-Wav signaling circuit, a transinitter and `a.transformerhaving windings of different impedances,V means 'for estabf Alishing a transmissio-npath for .talking from-,100

the transmitter through the transformer in the directionfrom the Vone of said windings having ,the ,loiverof said imnedancest'othe v .to said' one Winding` v'vh'erebv the impedance c ofsaid receiverjas Aviewed through said trans-V vfoil-meras greater than its actual impedancewiio ,to Vreceive.transmission through -said transformer inthe ,directionfrom saidy other `Windingtoisaid one Winding. i'

175. In a .two-Way signaling circuit.v a receiven fa transmitter, al vtransformer havingf ;l'15

windings of different impedances, means vfor establishing af transmission path for talk-V formerzin the'direction fromithe onecof said windings `hav-ingl the lower of -saidiinped-if-:lZO

ancesito-the other Winding, With the vreceiver. connectedto'a portionof said other Winding, inanti-side tone relationfto said transmitter, Y and means I.for disconnecting lsaid receiver `from -said other vvindingand connecting it 125 to the' opposite Aside of the transformer, whereby the impedance of said :receiver as viewed'through said transformer is greater ,than its actual impedancd'to receive `transmission throng-h; said transformer `11i the di- 1i130 Y:ro

rection fro-m said other winding to the Winding of lower impedance.

16. In combination, a transmitter, a receiver, a transformer, said transformerhav- :ing a relatively low impedance winding with a relatively low number of turns, and having a relatively high impedance winding with a relatively high number of tui'ns and with a relatively high resistance portion and a relatively low resistance portion, and means interconnecting said transmitter, said receiver and said transformer, saidmeans comprising switching means for, at one time, connecting said transmitter to said low impedance .winding and connecting said receiver to said high impedance winding in anti-side tone relation to said transmitter and in circuit with a portion of lsaid high impedance winding eX-l pensating forthe variation in said impedance. v

18. In a two-way signaling system, a circuit for the transmission and reception .of signals, a transmitting circuit proper, a receiving circuit proper, a ,balancing circuit,

Y and aV transformer with a plurality of windings, said elements being so proportioned and'related that said first mentioned circuit and said balancing circuit areconjugate, and

,Y said receiving circuit proper comprising receiving apparatus having an impedance tending to cause the impedance of said receiving circuit proper Ato vary with frequency and also comprising an impedance of suchcharacter and so related to said apparatus as to reduce saidvariation. l 19. In combination, two ysignaling. lines, two-way repeating. vmeans interconnecting said lines, and means vfor receiving signals from said lines, said lines being yconnected to said. receiving means inv substantially conjugate relation for preventing the transfer of signals from one of said lines to the other of ,said lines through said receiving means, and said means comprising a receiver and a resistance sliunted'there acrossto reduce the variation of the impedance across said receiver terminals with frequency.

20. The method of operating a signaling system including two two-wire circuits and a four-wire circuit connected to said two-wire circuits at points geographically remote from eachother, and a supervisory lset including a transmitter and a receiver, which coinprises at one time, maintaining said receiver in condition to monitor, on each side of said four-wire circuit, signals passing between said two wire circuits, at the saine time preventing transfer of signals between said two sides of said four-wire circuit, and at the saine time, maintaining said transmitter in condition to transmit to said four-wire circuit.

21. In'conibination, a four-wire signaling 'circuit comprising two one-way two-wire lines, means for receiving signals from each of said lines, said lines being lconnected to said receiving means in substantially conjugate relation for preventing transfer of signalsv from one of said lines tothe 'other of 'said lines through said receiving means, and

transmitting means for impressing signaling currents on said lines, said transmitting and receiving means being conjugate.

22. A monitoring circuit for a four-wire` signaling` system employing repeater coils, comprising monitoring windings inductively associated with the repeater coils, an operators substation set comprising a transmitter and a receiver, and connectionsfrom said substation set to each of a plurality of said monitoring. windings for balancing the impedance of one of said iiionitoringwindings against the impedance of another of said monitoring windings to render said` substation set anti-side tone when transmitting from said transmitter. V

23. VA, signaling system comprising two transmission lines, a two-way repeater cir- Sil cuit, a network forbalancing each of said V lines, al transformerfor associating one of said lines with one of said network's'and said repeater circuit, a second transformer for associating the otherof said lines with the second of said networks and said repeater circuits, an auxiliary winding` mounted on each ofsaid,transformers,f.a substation set comprising a transmitter, a receiver, a transformer having twowindings, connections from said substation set to said auxiliary windings Vfor impressing currents'from said transmitter serially upon 'said windings wliile'preventing side tone in said receiver, and means for changing the connections of said receiver from one-winding to the other winding of said last mentioned transformer.

24. In combination with a repeating system having a repeater with output transformers and monitoring windings on said transformers, a repeater attendants telephone set, comprising a receiver and a transmitter, normally arranged for amplified monitoring in both directions, said Vset comprising a monitoring key operable to one position to give amplified monitoring, through said repeater,in one direction, and operable to another-position to give amplified monitoring,

i through said repeater, in the other direction, and said set comprising a talking key operable to connect the transmitter fortransmission to said windings Ywith the impedance of one ofsaid windings balanced against the impedance of the other oi said Winding to render said receiver antiside tone with respect to said transmitter, said monitoring connecting said'receiving circuit .to receive signals from each of said lines, said. receiving circuit comprising'y receiving :appa-l ratus having an impedance tending Vto Acause the impedance of said receiving circuit to vary with frequencyl and Valso comprising an impedance of Vsuch character and so related to said apparatusV as to reduce said variation.A

26. In combina-tion, a four-Wire signaling circuit comprising t-Wo one-Way two-wire linesy and means Vfor receiving signals Jrfi-oni each of said lines, said lines being connect-ed to saidreceiving means in sub- "stantia-llyf conjugate relation for preventing transfer of signals fromrone of said lines to the other of said linesthrough'said receiving means, and said, receiving means comprising a receiver'having animpedancey varying with `frequency and also comprising an impedance of ksuch character and sore-- lated to said receiver as to reduce the varia? tion of impedance vacross the receiver termi# na-ls. i

27.l In combination, a four-Wire repeater comprising tivo oppositely directed one-Way two-Wire repeating paths and a tvvo-Waysig- `naling system comprising a circuit connected Vto one otsaid paths for the transmission andr reception of signals, a transmitting circuit pi-oper, a receiving circuit proper, a balanc- Y ing circuitl connected to the other of said paths, and a transformer with a plurality of Windings, said elements being so proportioned and Vrelated that saidvrst mentioned circuit andVZ Y said balancing circuit are conjugate ands'aid transmitting 'circuit proper andsaid receiv- :ing circuit vproper are. conjugate, and said receiving circuit proper comprising receiving Vapparatus having an impedance tending Y.

to cause -tliefimpedance of said receiving circuit proper -to' varywvith frequency and also vcoinprisingan impedanceof such char` acter and so related to said receiving appa- 1 ratus as tovreduce said variation.

.In `vvitnessfivliereof, I hereunto subscribe my name this 9th day `of February A.' D., i925. f

DONALDA. QUARLEs. 

